In the late 1920s and early 1930s, the Department of Commerce constructed large concrete arrows on the ground as visual navigational aids for the planes flying the transcontinental mail routes. In the day time the arrows, spaced at about 10 mile intervals, pointed the pilots to the next arrow.
Aerial Navigation Arrow
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skyeye
@ 2013-06-18 16:27:55
The upper tail of the arrow points toward San Francisco; the lower toward Los Angeles.